Apache Kafka + Apache Camel 集成 + POC 问题 + java.util.Hashtable.put(Hashtable.java:459) 处的 java.lang.NullPointerException

Question

这是我的路线建设者。 在这里，我试图将数据从我的文件插入到主题。后来，我正在通过我的主要方法并使用我正在运行的骆驼上下文。 我尝试了几个代码，但没有一个对我有帮助。 我正在研究 Apache kafka - Camel 的 POC。

public class SimpleRouteBuilder extends RouteBuilder {

    @Override
    public void configure() throws Exception {

        String topicName = "test120";
        String kafkaServer = "kafka:localhost:9092";
        String zooKeeperHost = "zookeeperHost=localhost&zookeeperPort=2181";
        String serializerClass = "serializerClass=kafka.serializer.StringEncoder";

        String toKafka =  "kafka:localhost:9092?topic=test120;zookeeperHost=localhost;zookeeperPort=2181;groupId=group1";


    //  toKafka = new StringBuilder().append("&").append(serializerClass).toString();

                /*new StringBuilder().append(kafkaServer).append("?").append(topicName).append("&")
                .append(zooKeeperHost).append("&").append(serializerClass).toString();*/

        from("file:C:/inbox?noop=true").to(toKafka);


    }
}

这是我的 pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>HelloWorld</groupId>
  <artifactId>Pallavi</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <dependencies>
      <dependency>
          <groupId>org.apache.camel</groupId>
          <artifactId>camel-core</artifactId>
          <version>2.20.1</version>
      </dependency>

      <dependency>
          <groupId>org.apache.camel</groupId>
          <artifactId>camel-kafka</artifactId>
          <version>2.20.1</version>
      </dependency>

      <dependency>
          <groupId>org.scala-lang</groupId>
          <artifactId>scala-library</artifactId>
          <version>2.11.0</version>
      </dependency>
  </dependencies>

</project>

这是我的主要课程：

import org.apache.camel.CamelContext;
import org.apache.camel.impl.DefaultCamelContext;

public class MainApp {

    public static void main(String[] args) {
        SimpleRouteBuilder routeBuilder = new SimpleRouteBuilder();
        CamelContext ctx = new DefaultCamelContext();
        try {
            ctx.addRoutes(routeBuilder);
            ctx.start();
            Thread.sleep(5 * 60 * 1000);
            ctx.stop();
            System.out.println("hi i am working");
        }
        catch (Exception e) {
            e.printStackTrace();
        }

    }
}

错误是：

java.lang.NullPointerException
    at java.util.Hashtable.put(Hashtable.java:459)
    at org.apache.camel.component.kafka.KafkaProducer.getProps(KafkaProducer.java:63)
    at org.apache.camel.component.kafka.KafkaProducer.doStart(KafkaProducer.java:89)
    at org.apache.camel.support.ServiceSupport.start(ServiceSupport.java:61)
    at org.apache.camel.util.ServiceHelper.startService(ServiceHelper.java:75)
    at org.apache.camel.impl.DeferServiceStartupListener.onCamelContextStarted(DeferServiceStartupListener.java:49)
    at org.apache.camel.impl.DefaultCamelContext.safelyStartRouteServices(DefaultCamelContext.java:3859)
    at org.apache.camel.impl.DefaultCamelContext.doStartOrResumeRoutes(DefaultCamelContext.java:3638)
    at org.apache.camel.impl.DefaultCamelContext.doStartCamel(DefaultCamelContext.java:3490)
    at org.apache.camel.impl.DefaultCamelContext.access$000(DefaultCamelContext.java:208)
    at org.apache.camel.impl.DefaultCamelContext$2.call(DefaultCamelContext.java:3249)
    at org.apache.camel.impl.DefaultCamelContext$2.call(DefaultCamelContext.java:3245)
    at org.apache.camel.impl.DefaultCamelContext.doWithDefinedClassLoader(DefaultCamelContext.java:3268)
    at org.apache.camel.impl.DefaultCamelContext.doStart(DefaultCamelContext.java:3245)
    at org.apache.camel.support.ServiceSupport.start(ServiceSupport.java:61)
    at org.apache.camel.impl.DefaultCamelContext.start(DefaultCamelContext.java:3168)
    at demo.MainApp.main(MainApp.java:13)
Picked up _JAVA_OPTIONS: -Xmx512M -Xms512M

Answer 1

我遵循了相同的教程。 但最初，我无法成功运行（谁使用最新版本的 kafka 服务器）。 我得到以下异常而不是空点异常：

org.apache.camel.FailedToCreateRouteException: Failed to create route route1 at: >>> Split[tokenize{body() using token: 
} -> [To[kafka:localhost:9092?topic=test&zookeeperHost=localhost&zookeeperPort=2181&serializerClass=kafka.serializer.StringEncoder]]] <<< in route: Route(route1)[[From[file:C:/input?noop=true]] -> [Split[toke... because of Failed to resolve endpoint: kafka://localhost:9092?serializerClass=kafka.serializer.StringEncoder&topic=test&zookeeperHost=localhost&zookeeperPort=2181 due to: Failed to resolve endpoint: kafka://localhost:9092?serializerClass=kafka.serializer.StringEncoder&topic=test&zookeeperHost=localhost&zookeeperPort=2181 due to: There are 2 parameters that couldn't be set on the endpoint. Check the uri if the parameters are spelt correctly and that they are properties of the endpoint. Unknown parameters=[{zookeeperHost=localhost, zookeeperPort=2181}]
    at org.apache.camel.model.RouteDefinition.addRoutes(RouteDefinition.java:1303)
    at org.apache.camel.model.RouteDefinition.addRoutes(RouteDefinition.java:204)
    at org.apache.camel.impl.DefaultCamelContext.startRoute(DefaultCamelContext.java:1143)
    at org.apache.camel.impl.DefaultCamelContext.startRouteDefinitions(DefaultCamelContext.java:3729)
    at org.apache.camel.impl.DefaultCamelContext.doStartCamel(DefaultCamelContext.java:3443)
    at org.apache.camel.impl.DefaultCamelContext.access$000(DefaultCamelContext.java:209)
    at org.apache.camel.impl.DefaultCamelContext$2.call(DefaultCamelContext.java:3251)
    at org.apache.camel.impl.DefaultCamelContext$2.call(DefaultCamelContext.java:3247)
    at org.apache.camel.impl.DefaultCamelContext.doWithDefinedClassLoader(DefaultCamelContext.java:3270)
    at org.apache.camel.impl.DefaultCamelContext.doStart(DefaultCamelContext.java:3247)
    at org.apache.camel.support.ServiceSupport.start(ServiceSupport.java:61)
    at org.apache.camel.impl.DefaultCamelContext.start(DefaultCamelContext.java:3163)
    at com.parane.kafka.demo.DemoApplication.main(DemoApplication.java:17)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)
Caused by: org.apache.camel.ResolveEndpointFailedException: Failed to resolve endpoint: kafka://localhost:9092?serializerClass=kafka.serializer.StringEncoder&topic=test&zookeeperHost=localhost&zookeeperPort=2181 due to: Failed to resolve endpoint: kafka://localhost:9092?serializerClass=kafka.serializer.StringEncoder&topic=test&zookeeperHost=localhost&zookeeperPort=2181 due to: There are 2 parameters that couldn't be set on the endpoint. Check the uri if the parameters are spelt correctly and that they are properties of the endpoint. Unknown parameters=[{zookeeperHost=localhost, zookeeperPort=2181}]
    at org.apache.camel.impl.DefaultCamelContext.getEndpoint(DefaultCamelContext.java:758)
    at org.apache.camel.util.CamelContextHelper.getMandatoryEndpoint(CamelContextHelper.java:80)
    at org.apache.camel.model.RouteDefinition.resolveEndpoint(RouteDefinition.java:219)
    at org.apache.camel.impl.DefaultRouteContext.resolveEndpoint(DefaultRouteContext.java:115)
    at org.apache.camel.impl.DefaultRouteContext.resolveEndpoint(DefaultRouteContext.java:121)
    at org.apache.camel.model.SendDefinition.resolveEndpoint(SendDefinition.java:62)
    at org.apache.camel.model.SendDefinition.createProcessor(SendDefinition.java:56)
    at org.apache.camel.model.ProcessorDefinition.createProcessor(ProcessorDefinition.java:511)
    at org.apache.camel.model.ProcessorDefinition.createOutputsProcessorImpl(ProcessorDefinition.java:474)
    at org.apache.camel.model.ProcessorDefinition.createOutputsProcessor(ProcessorDefinition.java:441)
    at org.apache.camel.model.ProcessorDefinition.createOutputsProcessor(ProcessorDefinition.java:185)
    at org.apache.camel.model.ProcessorDefinition.createChildProcessor(ProcessorDefinition.java:204)
    at org.apache.camel.model.SplitDefinition.createProcessor(SplitDefinition.java:101)
    at org.apache.camel.model.ProcessorDefinition.makeProcessorImpl(ProcessorDefinition.java:562)
    at org.apache.camel.model.ProcessorDefinition.makeProcessor(ProcessorDefinition.java:523)
    at org.apache.camel.model.ProcessorDefinition.addRoutes(ProcessorDefinition.java:239)
    at org.apache.camel.model.RouteDefinition.addRoutes(RouteDefinition.java:1300)
    ... 17 more
Caused by: org.apache.camel.ResolveEndpointFailedException: Failed to resolve endpoint: kafka://localhost:9092?serializerClass=kafka.serializer.StringEncoder&topic=test&zookeeperHost=localhost&zookeeperPort=2181 due to: There are 2 parameters that couldn't be set on the endpoint. Check the uri if the parameters are spelt correctly and that they are properties of the endpoint. Unknown parameters=[{zookeeperHost=localhost, zookeeperPort=2181}]
    at org.apache.camel.impl.DefaultComponent.validateParameters(DefaultComponent.java:215)
    at org.apache.camel.impl.DefaultComponent.createEndpoint(DefaultComponent.java:139)
    at org.apache.camel.impl.DefaultCamelContext.getEndpoint(DefaultCamelContext.java:711)
    ... 33 more 

正如克劳斯·易卜生所提到的，您需要添加

经纪人

代码示例

toKafka="kafka://localhost:9092?topic=test&brokers=localhost:9092";

我希望这对遵循教程的人有所帮助。

Answer 2

您需要在端点上配置brokers选项。 或者全局在 kafka 组件上。

我已经记录了一张票，让 Camel 在下一个版本中报告更好的例外： https : //issues.apache.org/jira/browse/CAMEL-12090

这里有一个 Kafka 示例，您也可以查看： https : //github.com/apache/camel/tree/master/examples/camel-example-kafka

Answer 3

可能您没有设置为 Kafka 生产者提供配置的生产者属性。

骆驼的 Kafka 组件需要使用强制性的 Kafka 生产者属性进行配置。

Answer 4

确保目录C:\\inbox确实存在。 另外，请确保将 pom 文件中的依赖项版本更改为教程中提到的版本，因为自camel-kafka 2.17.0以来情况发生了变化，并且它不再像toKafka字符串那样接受zookeeperHost和zookeeperPort值.